MER (Marketing Efficiency Ratio)
MER is total revenue divided by total marketing spend across all channels, giving a blended view of marketing efficiency.
MER (sometimes called blended ROAS or ecosystem ROAS) looks at all revenue and all marketing spend together, ignoring per-channel attribution. It answers: for every dollar we spend on marketing as a whole, how much total revenue does the business generate?
MER became popular as iOS 14.5+ privacy changes degraded per-channel attribution accuracy. Because it uses top-line numbers from your store and bank account, it's immune to pixel and attribution errors.
MER is best used as a north-star health metric. It won't tell you which channel to scale, but it will tell you whether your overall marketing machine is efficient. Pair it with channel-level ROAS for tactical decisions.
Formula
MER = Total revenue ÷ Total marketing spend
Example
Related terms
ROAS
ROAS is the revenue earned for every dollar spent on advertising, expressed as a multiple (4x means $4 back per $1 spent).
CAC
CAC is the total cost of acquiring a new customer, including all marketing and sales spend across every channel.
POAS
POAS is the gross profit generated for every dollar of ad spend, giving a more accurate profitability measure than ROAS.
Attribution Window
An attribution window is the period after an ad interaction during which a conversion is credited to that ad — e.g. 7-day click.